Thermodynamic modelling of a twin-stage claw vacuum pump and its gas pressurization analysis

Multi-stage claw vacuum pumps are crucial in various industrial applications for efficiently achieving high vacuum levels compared to other positive displacement vacuum pumps. In order to elucidate the gas pressurization process of the multi-stage claw vacuum pump and clarify its structural design principles, the authors investigated a twin-stage claw vacuum pump as the main research subject, and analyzed its working characteristic. A thermodynamic model of the twin-stage claw vacuum pump describing the pressurization process was established, and the results were verified by means of experiments. Moreover, effects of the phase difference φ_Ⅰ-Ⅱ, the first-stage discharge port angle θ_d,Ⅰ and the thickness ratio B₁:B₂ on pump performance were discussed. Results show that as φ_Ⅰ-Ⅱ increases, the pump power of the first stage gradually increases, while the power of the second stage decreases and then increases. With the increase of θ_d,Ⅰ, the pump power decreases and then increases. When the suction pressure is 10 kPa, the specific power reaches its minimum value under B₁: B₂ = 2:1. As the suction pressure increases, the pump power gradually increases, and its specific power fells substantially and then levels out. These contents are of great significance for the design and optimization of multi-stage claw vacuum pumps.